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1.
Diisopropylidenated a-D-glucofuranose (1) was oxidated with CrO;-Pyridine complex. Oxidated product and its hydrate were separated and were reduced together to synthesize diisopro-pylidenated a-D-allofuranose (3 ). The yield of 3 increased by 8% than that with only oxidated prod-uct as reduction substrate. Benzoylated derivative of 3 was selectively hydrolyzed and dimesylated to synthesize 3-O-benzoyl-l ,2-O-isopropylidene-a-D-allofuranose (5) and its dimesylated deriva-tive respectively. The overall yield of 5 from 1 was 36%. Each step and final products were analyzed by 'H-NMR spectra and other methods. The experiments showed that the influence of acetic acid concentration on selective hydrolysis was obvious. The hydrolysis yield was 81. 8%. Oxidation, re-duction and other procedures were practical and had application potential.  相似文献   

2.
The hydrolysate of waste sludge was used as the feedstock of biodiesel production, and its technological feasibility was investigated. Waste sludge, collected from No.3 Municipal Wastewater Treatment Plant of Xi＇an, was hydrolyzed in two parallel reactors firstly. Yeast was added into one reactor for bioaugmentation, and the other reactor without yeast was used as a control. Then an acid-catalyzed in situ esterification process was carried out to convert the hydrolysate to biodiesel. The results of hydrolysis showed that the reactor bioaugmented with yeast could promote hydrolysis compared with the control one because of an obvious variance in total suspended solid （TSS）, volatile suspended solid （VSS） and soluble chemical oxygen demand （SCOD）. Furthermore, gas chromatography （GC） analysis exhibited that the total volatile fatty acid （VFA） was low in the hydrolysate of bioaugmentation reactor; however, its yield of the fatty acid methyl esters （FAMEs） by in situ esterification was obviously higher when compared with the control one. Therefore, it may be inferred that the hydrolysate of bioaugmentation was mainly inclined to longer-chain fatty acid rather than to VFA. Anyway, an FAMEs yield of 9.24% （wt%） from dried sludge was attained after the 12-d bioaugmentation hydrolysis and succedent esterification. This value was not only higher than that of the control one but also higher than that reported in previous literature. The above results illuminated that it was feasible to produce biodiesel from the bioaugmented hydrolysate of waste sludge.  相似文献   

3.
Raw corn starch granules were hydrolysized by glucoamylase in a chemostat. The hydrolysis of three different-sized granules shows that smaller granules undergo more hydrolyzation than larger ones. After 78 h, 97% of the granules was hydrolysized with diameter between 0.15 mm and 0.3 mm at 50℃. When corn starch concentration increased from 100 g/L to 250 g/L, the amount of reducing sugar produced was proportional to the initial substrate concentration and no substrate inhibition phenomenon appeared. In order to study the product inhibition exactly, the product from hydrolysis reaction itself was added into the hydrolysis system at the beginning of starch hydrolysis.Product inhibition with different quantities of product added were studied in the initial several hours,during which period enzyme inactivation could be neglected and product inhibition could be studied separately. The experiments indicate that product inhibition happens when the additional quantity exceeds 9.56 g/L.  相似文献   

4.
Whey protein concentrate （WPC 80） and sodium caseinate were hydrolyzed by Protamex to 5%, 10%, 15%, and 20% degree of hydrolysis （DH）. WPC 80, sodium caseinate and their hydrolysates were then analyzed, compared and evaluated for their nutritional qualities. Their chemical composition, protein solubility, amino acid composition, essential amino acid index （EAA index）, biological value （BV）, nutritional index （NI）, chemical score, enzymic protein efficiency ratio （E-PER） and in vitro protein digestibility （IVPD） were determined. The results indicated that the enzymatic hydrolysis of WPC 80 and sodium caseinate by Protamex improved the solubility and IVPD of their hydrolysates. WPC 80, sodium caseinate and their hydrolysates were high-quality proteins and had a surplus of essential amino acids compared with the FAO/WHO/UNU （1985） reference standard. The nutritive value of WPC 80 and its hydrolysates was superior to that of sodium caseinate and its hydrolysates as indicated by some nutritional parameters such as the amino acid composition, chemical score, EAA index and predicted BV. However, the E-PER was lower for the WPC hydrolysates as compared to unhydrolyzed WPC 80 but sodium caseinate and its hydrolysates did not differ significantly. The nutritional qualities of WPC 80, sodium caseinate and their hydrolysates were good and make them appropriate for food formulations or as nutritional supplements.  相似文献   

5.
Chromatograms of tocopherol homologues were obtained by a column of analytical size （inner diameter （ID） 0.46 cm cm×10 cm） packed with silica gel. Adsorption isotherms and film mass-transfer coefficient were estimated from the chromatograms by using a general rate model, which considers axial dispersion, external mass-transfer and intraparticle diffusion. Based on the obtained isotherms and mass-transfer coefficient, the separation process of tocopherol homologues on simulated moving bed （SMB） was simulated using the same model. According to the simulated results, a mixture of α-, γ-, δ-tocopherols and other impurities was separated on an SMB equipment. The SMB equipment was composed of 8 columns of ID 2 cm× 1 0 cm, with 2 columns in each section. The solid phase was silica gel, and the mobile phase was n-hexane/2-propanol （99/1 by volume）. γ- and δ-tocopherols of purity greater than 98% were obtained with recovery greater than 98%. The effects of operating conditions （flow rates and switching time） on the performance of SMB were studied by both simulation and experiments. It was found that all the simulation results were quite close to the experimental results. We conclude that process development and optimization of operating conditions of SMB by simulation are feasible.  相似文献   

6.
1, 3：2, 4-di-p-methylbenzylidene-D-sorbitol （MDBS） is known to be an efficient sorbitol derivative gelator. Two new sorbitol derivative gelators were designed and synthesized in contrast to MDBS in order to study the gel properties of gelators with different structures. Their gelation behavior to 30 solvents was investigated. It was found that the gelation behavior was related to the molecular structure of gelators. Compared with MDBS, the gelator with more hydroxyl in the molecular structure could gel water and that with more aromatic ring could gel aromatic solvent. The fibrous and three-dimensional network of the gels was obtained by scanning electron microscopy （SEM）. Ultraviolet-visible （UV-Vis） spectroscopy revealed that π-π interaction was one of the main driving forces for the formation of gels. The π-π stacking of gelation increases with the number of aromatic rings in the molecular structure of gelator. Fourier transform infrared （FT-IR） spectroscopy revealed that the hydrogen bonding was also the main driving force for the formation of gels. The layered structure of the gels was studied by X-ray diffraction （XRD）.  相似文献   

7.
Self-made enriched 10 B boric acid as raw material was purified by recrystallization. The effects of final crystallization temperature, crystallization time, stirring speed, crystallization frequency and other factors on the purity were investigated. The appropriate operating condition was that the final crystallization temperature and time were 5,℃ and 10 h respectively under a low-speed stirring for crystallizing twice, which would make the purity and yield of boric acid reach 99.94% and 95.36%, respectively. Taking this as foundation, recrystallization process was optimized with acetone as anti-solvent, whose amount was the most important index. The boric acid solution was added into acetone and recrystallized under the same condition, and the purity and yield of boric acid would reach 99.98% and 99.61%, respectively. The product detected by XRD was confirmed as boric acid crystal. Main ion concentration in the product was detected by ICP, which basically met the national standard of high purity. Crystal morphology of boric acid was observed by SEM.  相似文献   

8.
Feng  Fang  Zhou  Qingqing  Yang  Yanfang  Zhao  Fangkun  Du  Renpeng  Han  Ye  Zhou  Zhijiang 《天津大学学报(英文版)》2019,25(1):78-84
A linear glucan was produced by Lactobacillus sake L-7 isolated from homemade sausage. Cultivation of the strain in Man–Rogosa–Sharpe(MRS) medium containing 50 g/L sucrose yielded 5.3 g/L of purified exopolysaccharide(EPS). The EPS was characterized by gas chromatography(GC), Fourier-transform infrared(FT-IR) spectroscopy, high-performance sizeexclusion chromatography(HPSEC), nuclear magnetic resonance(NMR) spectroscopy, and scanning electron microscopy(SEM). The monosaccharide composition of the EPS was glucose, and its molecular weight was 1 × 10~7 Da. The FT-IR and NMR spectra revealed that the L-7 EPS was a linear glucan with α-(1 → 6) glucosidic bonds. SEM images of the dried EPS revealed a hollow tubular structure. The water solubility index and water holding capacity of L-7 EPS were 96 and 272%, respectively. The results of hydrolysis indicated that L-7 EPS was not susceptible to hydrolysis by physiological barriers and can be used as a soluble dietary fiber with health benefits. All these characteristics suggest that L-7 EPS might have potential applications in the food, cosmetic, and pharmaceutical industries.  相似文献   

9.
In order to clarify the equilibrium components in the hydrolysis solution of boron trifluoride(BF_3-H_2O),the BF_3-H_2O was prepared by mixing BF_3-CH_3OH with large amount of water,in which the stoichiometric concentration of BF_3 is less than 0.1 mol/L.Two ionic equilibrium models were proposed to simulate the hydrolysis equilibrium of BF_3 and tested by special acid-base titration technique.The most accurate ion equilibrium constants were determined.The model,which was assumed to have no HF,was proved to be more representative for the real system and used to simulate the hydrolysis equilibrium of BF_3.The simulation suggested that H~+,BF_4~-,BF_3OH~- and H_3BO_3 were the main species in the dilute hydrolysis solution,while BF_2(OH)_2~- and F~- were insignificant species whose concentrations were both in the order of 10~(-4) mol/L magnitude,and BF(OH)_3~- could be omitted because its concentration almost equaled zero.Meanwhile,the equilibrium constant of the overall ionic reaction at 25℃ was obtained as 161.6.  相似文献   

10.
Synthesis of Enriched 10B Boric Acid of Nuclear Grade   总被引：2，自引：2，他引：0  
An economic and effective method of preparing enriched 10 B boric acid was established by chemical reaction of enriched 10BF3 and CaCO3. A process of boron trifluoride reacting with water was investigated under certain conditions. Calcium carbonate was selected to counteract hydrofluoric acid followed on. Some key operation factors were investigated, such as temperature, reaction time and the ratio of CaCO3 to 10BF3. The results showed that the yield of enriched 10 B boric acid could reach 97. 2% and the purity was up to 94. 1% under the following conditions: the temperature was 50—60,℃, the reaction time was 28 h and the ratio of CaCO3 to 10BF3 was 4. In addition, after recrystallization and titration analysis, the purity of the product could reach over 99. 2% from 94.1%.  相似文献   

11.
The urea nitrogen adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose （CDAC） and immobilized urease in gelatin membrane （IE）, was prepared. The cellulose, the dialdehyde cellulose （DAC） and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10：1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37℃.  相似文献   

12.
The separation of ternary methanol/methyl butyl ether/1-butylchloride mixtures was investigated, which are the main components of the waste liquid. After preliminary studies on the ternary system, the integrated process of extraction and distillation was put forward to separate the ternary system. The results show that methanol carl be removed from the mixtures by extraction using water as the extracting agent. Through distillation of extract and dried raffinate respectively, methanol, methyl butyl ether and 1-butylchloride can be separated and recovered. In addition, the optimal volume for the extracting agent and effects of reflux ratio on the yield of product were also studied. The optimal volume ratio of the extracting agent to material is 1： 3.5, and the yield of the product increases with the increase of reflux ratio.  相似文献   

13.
Non-a-tocopherols are hydroxymethylated and hydrogenated to produce α-tocopherol in one pot process by simultaneously reacting with paraformaldehyde and hydrogen in the presence of catalysts of benzenesulfonic acid and 5% Pd/C in an autoclave. Effects of various operation conditions have been studied. The preferable reaction conditions are: temperature 180 ℃ to 200 ℃, pressure 5.0 MPa, acid concentration 0.5 g/100 ml ethanol, mass ratio of Pd/C to tocopherols 7.1 g/100 g, and reaction time 5.0 h. A product with α-tocopherol content of 80% was obtained by using a raw material with a total tocopherols content of 80.54%. The conversion of non-α-tocopherols is almost 100%, and the mole yield of a-tocopherol is more than 90%.  相似文献   

14.
To investigate the mechanical behavior of segmental lining,a three-dimensional numerical analysis and test using three actual segments were used to analyze the effects of axial force and reinforcement ratio on the failure mechanism and ultimate bearing capacity of segmental lining.Both numerical and test results confirmed that the cracking load,yield and ultimate load were strongly influenced by axial force,and it was also proved that the yield and ultimate load would increase with the increase of reinforcement ratio,but the cracking load was almost not affected.The cracking load,yield and ultimate load are about 28.7%,500% and 460% larger due to the effect of axial force respectively.The comparison between numerical calculation and test results showed that the finite element analysis results were in good agreement with the test results.  相似文献   

15.
Fluidized-bed reactor is a candidate for dimethyl ether （DME） synthesis from syngas because of its excellent heat removal capability. In order to improve the attrition resistance of catalyst, an amount of silica sol as binder was added to the catalyst composed of methanol synthesis component CuO/ZnO/Al2O3 and methanol dehydration component HZSM-5, which was prepared by coprecipitation and shaped by spray drying to get spherical particles. The effect of silica sol on the catalytic activity was investigated in a fixed-bed flow microreactor. Based on the experiment results, silica sol in the range of 0-20wt% had small effect on the catalytic activity. Generally, the CO conversion and DME yield decreased with the increase in concentration of silica sol, while the attrition resistance of catalysts increased with increasing silica sol, indicating that it was feasible to improve the attrition resistance without greatly sacrificing the activity of catalyst. In addition, the characterizations of catalysts were carried out using Brunauer-Emmett-Teller （BET）, X-ray powder diffraction （XRD） and temperature programmed reduction （TPR）.  相似文献   

16.
The kinetics of extraction and stripping of copper （Ⅱ） was investigated by the single drop technique with a new extractant N902 （a derivative of the salicylal-doxime） and the rate equations of extraction and stripping were derived, respectively. The apparent activation energies of extraction and stripping were estimated to be 20.14 kJ/mol and 30.0 k J/mol.  相似文献   

17.
To evaluate the strength attenuation law of soft rock in the western mining area of China, we established an evolution model for the strength parameters of soft mudstone at the post-peak stage by employing a tri-linear strain softening model. In the model, a stiffness degradation coefficient co and a softening modulus coefficient a were introduced to take into account the stiff- ness degradation, and the subsequent yield surfaces at post-peak stage were all assumed to meet the Molar-Coulomb yield criterion. Furthermore, attenuation laws of stiffness and strength parameters of soft mudstone were analyzed according to an engineering case. Finally, the model＇s accuracy was verified by comparison of results from numerical calculation and tri-axial compression tests. Results showed that the attenuation of the friction angle was dominated mainly by the instantaneous stress states and damage features, while the attenuation law of cohesion was also related to the plastic behavior. The degradation rates of strength param- eters decreased with increasing confining pressure and the friction angle tended towards its initial value. Residual strengths were also enhanced with increasing confming pressure. The results indicate that the evolution model can accurately describe the strain softening behavior of soft rock.  相似文献   

18.
Calcium carbide slag, generated in the hydrolysis process of calcium carbide, is an potential carbon capture reagent because its main ingredient is Ca(OH)2. Calcium carbide slag, a by-product of a resin factory was used as carbon capture reagent. The change of pH and electrical conductivity (EC) of the calcium carbide slag slurry with different solid-to-liquid ratios, as well as the capture efficiency and dynamics under different temperatures and flow rates of CO2 were studied. The properties of solid were characterized with XRD, TG-DTA, SEM and FT-IR before and after capturing carbon. The results show that the change of pH and EC were greater with low solid-to-liquid ratio than that with high solid-to-liquid ratio. The analysis of XRD and SEM show that the content of CaCO3 increased significantly, which improved that Ca(OH)2 and free CaO were reacted with CO2. The results of TG-DTA and FT-IR show that the physicochemical properties and microstructure of the slag changed after capturing CO2 because of the increase of CaCO3 content. All the results mentioned above improve the feasibility of utilizing calcium carbide slag to capture CO2 and offer a practical way for carbon emission reduction and disposal of wasted calcium carbide slag.  相似文献   

19.
Biotransformation of phytosterol(PS) by a newly isolated mutant Mycobacterium neoaurum ZJUVN-08 to produce androstenedione has been investigated in this paper.The parameters of the biotransformation process were optimized using fractional factorial design and response surface methodology.Androstenedione was the sole product in the fermentation broth catalyzed by the mutant M.neoaurum ZJUVN-08 strain.Results showed that molar ratio of hydroxypropyl-β-cyclodextrin(HP-β-CD) to PS and substrate concentrations were the two most significant factors affecting androstenedione production.By analyzing the statistical model of three-dimensional surface plot,the optimal process conditions were observed at 0.1 g/L inducer,pH 7.0,molar ratio of HP-β-CD to PS 1.92:1,8.98 g/L PS,and at 120 h of incubation time.Under these conditions,the maximum androstenedione yield was 5.96 g/L and nearly the same with the non-optimized(5.99 g/L),while the maximum PS conversion rate was 94.69% which increased by 10.66% compared with the non-optimized(84.03%).The predicted optimum conditions from the mathematical model were in agreement with the verification experimental results.It is considered that response surface methodology was a powerful and efficient method to optimize the parameters of PS biotransformation process.  相似文献   

20.
The objective of this work was to investigate the effect of six individual strains of fungi on the reduction of gossypol levels and nutritional value during solid substrate fen＇aentation of cottonseed meal （CSM）. Six groups of disinfected CSM substrate were incubated for 48 h after inoculation with either of the fungi C. capsuligena ZD- 1, C. tropicalis ZD-3, S. cerevisae ZD-5, A. terricola ZD-6, A. oryzae ZD-7, or A. niger ZD-8. One not inoculated group （substrate） was used as a control. Levels of initial and final free gossypol （FG）, crude protein （CP）, amino acids （AA） and in vitro digestibility were assayed. The experiment was done in triplicate. The experimental results indicated that microbial fermentation could greatly decrease （P〈0.05） FG levels in CSM. The detoxification efficiency differed between the species of microorganisms applied. From the perspective of reducing CSM potential toxicity, C. tropicalis ZD-3 was most successful followed by S. cerevisae ZD-5 and A. niger ZD-8. They could reduce FG levels of CSM to 29.8, 63.07 and 81.50 mg/kg based on DM （dry matter）, respectively, and their detoxification rates were 94.57%, 88.51% and 85.16%, respectively. If crude protein, amino acids content and their in vitro digestibility were also taken into account, Aniger ZD-8 may be the best choice. The CP content of CSM substrate fermented by C. tropicalis ZD-3 and A. niger ZD-8 were improved by 10.76% and 22.24%; the TAA （total amino acids） contents were increased by 7.06% and 11.46%, and the EAA （essential amino acids） were raised by 7.77% and 12.64%, respectively. Especially, the levels of methionine, lysine and threonine were improved greatly （P〈0.05）. The in vitro CP digestibility of CSM fermented by C. tropicalis ZD-3 and A. niger ZD-8 was improved by 13.42% and 18.22%, the TAA were increased by 17.75% and 22.88%, and the EAA by 16.61% and 21.01%, respectively. In addition, the in vitro digestibility of methionine, lysine and threonine was also improved greatly （P〈0.05）.  相似文献   

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